Allow the code to compile without an entropy floor.

src/entropy_floor/EAGLE/entropy_floor.h

@@ -206,10 +206,15 @@ static INLINE void entropy_floor_init(struct entropy_floor_properties *props,
       props->Cool_density_threshold;
 }
 
+/**
+ * @brief Print the properties of the entropy floor to stdout.
+ *
+ * @param props The entropy floor properties.
+ */
 static INLINE void entropy_floor_print(
     const struct entropy_floor_properties *props) {
 
-  message("Entropy floor is EAGLE with:");
+  message("Entropy floor is 'EAGLE' with:");
   message("Jeans limiter with slope n=%.3f at rho=%e (%e H/cm^3) and T=%.1f K",
           props->Jeans_gamma_effective, props->Jeans_density_threshold,
           props->Jeans_density_threshold_H_p_cm3,

src/entropy_floor/none/entropy_floor.h

@@ -25,4 +25,78 @@
  * floors.
  */
 
+/**
+ * @brief Properties of the entropy floor.
+ *
+ * Nothing here.
+ */
+struct entropy_floor_properties {};
+
+/**
+ * @brief Compute the entropy floor of a given #part.
+ *
+ * Simply return 0 (no floor).
+ *
+ * @param p The #part.
+ * @param cosmo The cosmological model.
+ * @param props The properties of the entropy floor.
+ */
+static INLINE float entropy_floor(
+    const struct part *p, const struct cosmology *cosmo,
+    const struct entropy_floor_properties *props) {
+
+  return 0.f;
+}
+
+/**
+ * @brief Initialise the entropy floor by reading the parameters and converting
+ * to internal units.
+ *
+ * Nothing to do here.
+ *
+ * @param params The YAML parameter file.
+ * @param us The system of units used internally.
+ * @param phys_cont The physical constants.
+ * @param props The entropy floor properties to fill.
+ */
+static INLINE void entropy_floor_init(struct entropy_floor_properties *props,
+                                      const struct phys_const *phys_const,
+                                      const struct unit_system *us,
+                                      const struct hydro_props *hydro_props,
+                                      struct swift_params *params) {}
+
+/**
+ * @brief Print the properties of the entropy floor to stdout.
+ *
+ * @param props The entropy floor properties.
+ */
+static INLINE void entropy_floor_print(
+    const struct entropy_floor_properties *props) {
+
+  message("Entropy floor is 'no entropy floor'.");
+}
+
+/**
+ * @brief Write an entropy floor struct to the given FILE as a stream of bytes.
+ *
+ * Nothing to do here.
+ *
+ * @param props the struct
+ * @param stream the file stream
+ */
+static INLINE void entropy_floor_struct_dump(
+    const struct entropy_floor_properties *props, FILE *stream) {}
+
+/**
+ * @brief Restore a entropy floor struct from the given FILE as a stream of
+ * bytes.
+ *
+ * Nothing to do here.
+ *
+ * @param props the struct
+ * @param stream the file stream
+ */
+static INLINE void entropy_floor_struct_restore(
+    struct entropy_floor_properties *props, FILE *stream) {}
+
 #endif /* SWIFT_ENTROPY_FLOOR_NONE_H */